Take your square piece of paper. . .
And fold it in half DIAGONALLY.
Fold it in half again.
Unfold the last step.
Take BOTH corners of the paper on top and fold them down so they touch the bottom of the triangle.
Take the right corner and fold it along the edge of the paper that you folded last step.
Do the same with the other side.
Turn the whole thing over.
Fold one of the top corners down (doesn't matter which one).
And fold it up again so the corner reaches just below of the one next to it.
Then, tuck it under the paper.
Turn it over. . .
And fold the bottom corner up.
There you have it! Your completed sailboat!
That even stands up!